Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/22—Compounding polymers with additives, e.g. colouring using masterbatch techniques
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C1/00—Tyres characterised by the chemical composition or the physical arrangement or mixture of the composition
  • B60C1/0016—Compositions of the tread
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K5/00—Use of organic ingredients
  • C08K5/0008—Organic ingredients according to more than one of the "one dot" groups of C08K5/01 - C08K5/59
  • C08K5/0016—Plasticisers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2307/00—Characterised by the use of natural rubber
  • C08J2307/02—Latex
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2321/00—Characterised by the use of unspecified rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/002—Physical properties
  • C08K2201/006—Additives being defined by their surface area

Definitions

• the invention relates to a rubber composition in particular for a tire tread, and more particularly for a tire intended to equip vehicles carrying heavy loads and traveling at a high speed, such as, for example, trucks, tractors, trailers or road buses. , plane etc.
• thinner reinforcing fillers especially so-called “fine” carbon blacks, that is, that is to say having a CTAB specific surface greater than or equal to 90 m 2 / g, or even so-called “very fine” blacks, that is to say carbon blacks having a CTAB specific surface greater than or equal to 130 m 2 / g.
• the subject of the invention is thus a rubber composition based on at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface area greater than or equal to 130 m 2 / g, a plasticizing oil and a crosslinking system, the dispersion of the filler in the elastomeric matrix having a Z score greater than or equal to 70.
• the level of plasticizing oil in the composition varies from 2 to 50 parts per hundred parts by weight of elastomer, preferably from 5 to 25 phr.
• the composition is obtained from a first masterbatch comprising at least the diene elastomer and the carbon black, and having a dispersion of carbon black in the elastomeric matrix having a Z rating greater than or equal to 80.
• the first masterbatch is obtained by mixing in the liquid phase from a diene elastomer latex and an aqueous carbon black dispersion.
• a masterbatch of diene elastomer and reinforcing filler there are different methods for obtaining a masterbatch of diene elastomer and reinforcing filler.
• one type of solution consists in improving the dispersibility of the filler in the elastomeric matrix by mixing the elastomer and the "liquid" phase filler.
• an elastomer in the form of latex has been used in the form of elastomer particles dispersed in water, and an aqueous dispersion of the filler, that is to say a dispersed filler. in water, commonly called "slurry".
• This method consists in particular of incorporating a continuous flow of a first fluid constituted by an elastomer latex into the mixing zone of a coagulation reactor, to incorporate a second continuous flow of a second fluid consisting of an aqueous dispersion of pressurized charging in the mixing zone to form a mixture with the elastomer latex; the mixing of these two fluids being sufficiently energetic to allow the elastomer latex to be coagulated almost completely with the filler before the exit orifice of the coagulation reactor and then to dry the coagulum obtained.
• the subject of the invention is also a composition based on at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface area greater than or equal to 130 m 2 / g, a plasticizing oil and also a crosslinking system, obtained from a first masterbatch comprising at least the diene elastomer and the carbon black, and having a dispersion of the carbon black in the elastomeric matrix having a Z score greater than or equal to 80.
• the level of plasticizing oil in the composition ranges from 2 to 50 parts per hundred parts by weight of elastomer, preferably from 5 to 25 phr.
• the composition is obtained from a first masterbatch comprising at least the diene elastomer and the carbon black, and having a dispersion of carbon black in the elastomeric matrix having a note Z greater than or equal to 80.
• the first masterbatch is obtained by mixing in the liquid phase from a diene elastomer latex and an aqueous carbon black dispersion, preferably identical to the liquid phase process detailed above.
• the invention also relates to a method for preparing a composition comprising at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface area greater than or equal to 130 m 2 / g, a plasticizing oil as well as a crosslinking system, the dispersion of the filler in the elastomeric matrix having a Z score greater than or equal to 70, which comprises the following steps:
• a first masterbatch comprising at least the diene elastomer and the carbon black, and having a dispersion of the carbon black in the elastomeric matrix having a Z score greater than or equal to 80, is prepared prior to the incorporation of all the constituents of the composition in the mixer.
• the masterbatch is produced in the liquid phase from at least one elastomer latex and a carbon black dispersion, in particular according to the previously detailed above.
• the invention also relates to a method for preparing a composition comprising at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface area greater than or equal to 130 m 2 / g, a plasticizing oil as well as a crosslinking system, which comprises the following steps:
• first masterbatch comprising the diene elastomer and the carbon black
• this first masterbatch having a dispersion of the filler in the elastomeric matrix having a Z-score of greater than or equal to 80, incorporation of the other constituents of the composition, with the exception of the crosslinking system, at the first master batch in a mixer by thermomechanically kneading the whole until a maximum temperature of between 130 ° C and 200 ° C is reached,
• the masterbatch is made in the liquid phase from at least one elastomer latex and a carbon black dispersion, in particular according to the previously detailed above.
• the invention also relates to a masterbatch based on at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB surface area greater than or equal to 130 m 2 / g, a plasticizing oil, the dispersion of the filler in the elastomeric matrix having a Z score greater than or equal to 70.
• this masterbatch is obtained from a first masterbatch comprising at least the diene elastomer and the carbon black, and having a dispersion of the carbon black in the elastomeric matrix having a Z score greater than or equal to 80 .
• this first masterbatch is made in the liquid phase from at least one elastomer latex and a carbon black dispersion, in particular according to the previously detailed above.
• the invention also relates to a masterbatch based on at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface area greater than or equal to 130 m 2 / g, a plasticizing oil obtained from a first masterbatch comprising at least the diene elastomer and the carbon black, and having a dispersion of the carbon black in the elastomeric matrix having a Z score greater than or equal to 80.
• this first masterbatch is made in the liquid phase from at least one elastomer latex and a carbon black dispersion, in particular according to the previously detailed above.
• the invention finally relates to a finished or semi-finished article, a tire tread, a tire and a semi-finished product comprising a composition as described above or a master batch as described above.
• masterbatch is used herein to refer to an elastomer-based composite in which a filler and possibly other additives have been introduced.
• the rubber compositions are characterized, before and after firing, as indicated below.
• the charge dispersion in an elastomeric matrix can be represented by the note Z, which is measured, after crosslinking, according to the method described by S. Otto and Al in Kautschuk Kunststoffe, 58 Ciphergang, NR 7- 8/2005, in accordance with ISO 11345.
• the calculation of the Z score is based on the percentage of area in which the charge is not dispersed ("% undispersed area"), as measured by the "disperGRADER +" apparatus supplied with its operating mode and software. 'disperDATA' exploitation by Dynisco according to the equation:
• the percentage of undispersed surface is measured by a camera observing the surface of the sample under 30 ° incident light.
• the bright spots are associated with filler and agglomerates, while the dark spots are associated with the rubber matrix; digital processing transforms the image into a black and white image, and allows the determination of the percentage of undispersed surface, as described by S. Oto in the aforementioned document.
• a Z score greater than or equal to 80 corresponds to a surface having a very good dispersion of the filler in the elastomeric matrix.
• the dynamic properties including tan ( ⁇ ) max are measured on a viscoanalyzer (Metravib VA4000), according to the ASTM D 5992-96 standard.
• the response of a sample of vulcanized composition (cylindrical specimen 4 mm in thickness and 400 mm 2 in section), subjected to a sinusoidal stress in alternating simple shear, at the frequency of 10 Hz, is recorded under normal conditions.
• temperature 23 ° C.
• ASTM D 1349-99 the measurement temperature is 60 ° C.
• the invention relates to a composition based on at least one diene elastomer, a reinforcing filler comprising at least carbon black having a CTAB specific surface area greater than or equal to 130 m 2 / g, a plasticizing oil and a coating system. crosslinking, the dispersion of the filler in the elastomeric matrix having a Z score greater than or equal to 70.
• this composition is obtained from a first masterbatch comprising at least the diene elastomer and the carbon black, and having a black dispersion of 80.
• any range of values designated by the expression "between a and b" represents the range of values from more than a to less than b (i.e. terminals a and b excluded) while any range of values designated by the term “from a to b” means the range from a to b (i.e., including the strict limits a and b).
• the composition according to the invention comprises at least a first diene elastomer and optionally a second elastomer identical or different from the first, which may or may not be a diene elastomer.
• elastomer or “diene” rubber must be understood in known manner an elastomer derived at least in part (ie, a homopolymer or a copolymer) of monomers dienes (monomers bearing two carbon-carbon double bonds, conjugated or not). These diene elastomers can be classified into two categories: “essentially unsaturated” or "essentially saturated”.
• essentially unsaturated is generally understood to mean a diene elastomer derived at least in part from conjugated diene monomers, having a level of units or units of diene origin (conjugated dienes) which is greater than 15% (mol%);
• diene elastomers such as butyl rubbers or copolymers of dienes and alpha-olefins of the EPDM type do not fall within the above definition and may in particular be described as "substantially saturated" diene elastomers ( low or very low diene origin, always less than 15%).
• the term “highly unsaturated” diene elastomer is particularly understood to mean a diene elastomer having a content of units of diene origin (conjugated dienes) which is greater than 50%.
• diene elastomers there are also natural rubber and synthetic elastomers.
• diene elastomer By synthetic diene elastomers which can be used in accordance with the invention, the term diene elastomer is more particularly understood to mean:
• (d) - a copolymer of isobutene and isoprene (butyl rubber), as well as the halogenated versions, in particular chlorinated or brominated, of this type of copolymer.
• conjugated dienes 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-di (C 1 -C 5) alkyl-1,3-butadienes, such as for example 2 3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-methyl-3-ethyl-1,3-butadiene, 2-methyl-3-isopropyl-1, 3-butadiene, aryl-1,3-butadiene, 1,3-pentadiene, 2,4-hexadiene.
• Suitable vinylaromatic compounds are, for example, styrene, ortho-, meta-, para-methylstyrene, the "vinyl-toluene" commercial mixture, para-tertiarybutylstyrene, methoxystyrenes, chlorostyrenes, vinylmesitylene, divinylbenzene, vinylnaphthalene.
• the copolymers may contain between 99% and 20% by weight of diene units and between 80% and 80% by weight of vinylaromatic units.
• the elastomers may have any microstructure which is a function of the polymerization conditions used, in particular the presence or absence of a modifying and / or randomizing agent and the amounts of modifying and / or randomizing agent used.
• the elastomers can be for example block, statistical, sequenced, microsequenced, and be prepared in dispersion or in solution; they may be coupled and / or starred or functionalized with a coupling agent and / or starring or functionalization.
• a coupling agent for example, a coupling agent for example;
• functional groups comprising a C-Sn bond or amino functional groups such as aminobenzophenone for example;
• an inorganic filler such as silica, mention may be made, for example, of silanol or polysiloxane functional groups having a silanol end (as described, for example, in FR 2,740,778 or US Pat. No.
• alkoxysilane groups as described for example in FR 2,765,882 or US 5,977,238), carboxylic groups (as described for example in WO 01/92402 or US 6,815,473, WO 2004/096865 or US 2006/0089445).
• polyether groups as described for example in EP 1 127 909 or US 6,503,973, WO 2009/000750 and WO 2009/000752.
• functionalized elastomers mention may also be made of elastomers (such as SBR, BR, NR or IR) of the epoxidized type.
• Suitable polybutadienes and in particular those having a content (mol%) in units -1.2 between 4%> and 80%> or those having a content (%> molar) in cis-1,4 greater than 80%> polyisoprenes, butadiene-styrene copolymers and in particular those having a Tg (glass transition temperature (Tg, measured according to ASTM D3418) between 0 ° C. and -70 ° C. and more particularly between -10 ° C.
• Tg glass transition temperature
• styrene content of between 5% and 60% by weight and more particularly between 20% and 50%, a content (%> molar) in -1,2 bonds of the butadiene part between 4% and 75%, a content (mol%) of trans-1,4 bonds of between 10% and 80%, butadiene-isoprene copolymers and in particular those having an isoprene content of between 5% and 90%.
• the isoprene-styrene copolymers and especially those having a styrene content included between 5% and 50% by weight and a Tg of between -5 ° C and -50 ° C.
• the isoprene-styrene copolymers those having a styrene content of between 5% and 50% by weight and more particularly of between 10% and 40%, and an isoprene content of between 15%, are especially suitable.
• the synthetic diene elastomer (s) according to the invention are preferably chosen from the group of highly unsaturated diene elastomers consisting of polybutadienes (abbreviated as "BR"), synthetic polyisoprenes (IR), butadiene copolymers, copolymers of isoprene and mixtures of these elastomers.
• BR polybutadienes
• IR synthetic polyisoprenes
• butadiene copolymers copolymers of isoprene and mixtures of these elastomers.
• Such copolymers are more preferably selected from the group consisting of butadiene-styrene copolymers (SBR), isoprene-butadiene copolymers (BIR), isoprene-styrene copolymers (SIR) and isoprene-copolymers.
• SBIR butadiene-styrene
• the liquid phase mixing processes are preferably used to obtain masterbatches based on diene elastomer and carbon black having a very good dispersion of carbon black in the elastomer .
• a diene elastomer latex will be used more particularly, the elastomer latex being a particular form of the elastomer which is in the form of particles. of elastomer dispersed in water.
• the invention therefore preferably relates to diene elastomer latices, the diene elastomers being those defined above.
• NR natural rubber
• this natural rubber exists in different forms as detailed in Chapter 3 "Latex concentrates: properties and composition", K.F. Gaseley, A.D.T. Gordon and T. D. Pendle in “Natural Rubber Science and Technology", A. D. Roberts, Oxford University Press - 1988.
• the NR latex may be modified beforehand physically or chemically (centrifugation, enzymatic treatment, chemical modification, etc.)
• the latex can be used directly or be previously diluted in water to facilitate its implementation.
• the latex may in particular consist of a synthetic diene elastomer already available in the form of an emulsion (for example a copolymer of butadiene and styrene, SBR, prepared in emulsion), or a diene elastomer synthetic solution initially (for example a SBR prepared in solution) which is emulsified in a mixture of organic solvent and water, generally by means of a surfactant.
• a synthetic diene elastomer already available in the form of an emulsion for example a copolymer of butadiene and styrene, SBR, prepared in emulsion
• SBR styrene
• SBR latex in particular an emulsion-prepared SBR (“ESBR”) or an SBR prepared in solution (“SSBR”), and more particularly an SBR prepared in emulsion.
• ESBR emulsion-prepared SBR
• SSBR SBR prepared in solution
• an SBR elastomer In the case of an SBR elastomer (ESBR or SSBR), an SBR having an average styrene content, for example between 20% and 35% by weight, or a high styrene content, for example 35 to 35% by weight, is used in particular. 45%, a vinyl ring content of the butadiene part of between 15% and 70%, a content (mol%) of trans-1,4 bonds of between 15% and 75% and a Tg of between -10 ° C. and - 55 ° C; such an SBR can be advantageously used in admixture with a BR preferably having more than 90% (mol%) of cis-1,4 bonds.
• one or more natural rubber latexes may be used in the form of a blend, one or more synthetic rubber latexes in a blend or a blend of one or more natural rubber latexes with one or more synthetic rubber latexes.
• non-dienic butyl elastomers such as poly (isobutylene) homopolymers or poly-based copolymers are particularly suitable ( isobutylene) (of course in the case of copolymers with isoprene, the diene elastomers described above), as well as the halogenated derivatives, in particular those which are generally brominated or chlorinated, of these poly (isobutylene) homopolymers and copolymers based on poly (isobutylene).
• non-diene elastomers include copolymers of isobutylene and styrene derivatives, such as isobutylene and brominated methylstyrene copolymers (BIMS), of which an elastomer named EXXPRO sold by the company Exxon in particular is part.
• BIMS isobutylene and brominated methylstyrene copolymers
• non-diene elastomer particularly suitable for the invention of non-dienic thermoplastic elastomers (TPE).
• TPE thermoplastic elastomers
• the weight fraction of the first diene elastomer in the elastomeric matrix is greater than or equal to 50% and preferably greater than or equal to 60%.
• an organic filler consisting of carbon black is used.
• Suitable carbon blacks are all reinforcing carbon blacks having a CTAB specific surface area greater than or equal to 130 m 2 / g, and more particularly carbon blacks having an STAB surface greater than or equal to 160 m 2 / g. It should be noted that the CTAB specific surface area is determined according to the French standard NF T 45-007 of November 1987 (method B).
• one or more organic fillers may be combined in cross-cutting, such as, for example, functionalized organic polyvinylaromatic fillers as described in applications WO-A-2006/069792 and WO-A-2006/069793, and / or one or more reinforcing inorganic fillers such as silica.
• inorganic filler should be understood here, in a known manner, any inorganic or inorganic filler, regardless of its color and origin (natural or synthetic), also called “white” charge, “clear” charge or “non-black filler” charge as opposed to carbon black, this inorganic filler being able to reinforce on its own, with no other means than an intermediate coupling agent, a rubber composition intended for the manufacturing a tire tread, in other words able to replace, in its reinforcing function, a conventional tire grade carbon black for tread.
• Such a filler is generally characterized by the presence of functional groups, in particular hydroxyl (-OH), at its surface, requiring to be used as a reinforcing filler the use of an agent or coupling system intended to ensure a chemical bond. stable between the isoprene elastomer and said load.
• Such an inorganic filler can thus be used with a coupling agent to enable the strengthening of the rubber composition in which it is included. It can also be used with a coating agent (which does not provide a bond between the filler and the elastomeric matrix) in addition to a coupling agent or not (in this case the inorganic filler does not play a reinforcing role ).
• inorganic filler presents itself is indifferent, whether in the form of powder, microbeads, granules, beads or any other suitable densified form.
• inorganic filler is also understood to mean mixtures of different inorganic fillers, in particular highly dispersible siliceous and / or aluminous fillers as described below.
• Suitable inorganic fillers include mineral fillers of the siliceous type, in particular of silica (SiO 2), or of the aluminous type, in particular alumina (Al 2 O 3).
• the silica used may be any silica known to those skilled in the art, especially any precipitated or fumed silica having a BET surface and a CTAB specific surface both less than 450 m 2 / g, preferably from 30 to 400 m 2. /boy Wut.
• HDS highly dispersible precipitated silicas
• carbon black of fillers such as carbon blacks partially or wholly covered with silica by a post-treatment, or silica blacks modified in situ by silica, such as, without limitation the charges marketed by Cabot Corporation under the name Ecoblack TM "CRX 2000” or "CRX4000".
• the total charge rate (carbon black and inorganic filler such as silica) is between 20 and 200 phr, more preferably between 30 and 150 phr and even more preferably between 30 and 100 phr, the optimum being different known manner according to the particular applications concerned: the level of reinforcement expected on a bicycle tire, for example, is of course lower than that required on a tire able to run at high speed in a sustained manner, for example a motorcycle tire, a tire for passenger vehicles or commercial vehicles such as heavy goods vehicles.
• carbon black the content of which varies from 20 to 80 phr
• an inorganic filler in particular silica, the level of which varies from 5 to 50 phr, more particularly the total charge of the composition comprising carbon black, the content of which varies from 35 to 70 phr, and an inorganic filler, in particular silica, the content of which varies from 5 to 35 phr, so more preferably the total charge comprising carbon black whose rate varies from 40 to 65 phr and an inorganic filler, in particular silica, whose rate varies from 10 to 30 phr.
• the rubber compositions of the invention use an extender oil (or plasticizing oil) whose usual function is to facilitate the implementation, by a lowering of the Mooney plasticity and to improve the endurance by a reduction of the modules. lengthening to cooked.
• an extender oil or plasticizing oil
• these oils which are more or less viscous, are liquids (that is, as a reminder, substances having the capacity to take the form of containing them), in contrast to resins or rubbers which are inherently solid.
• the extender oil is chosen from the group consisting of polyolefinic oils (that is to say derived from the polymerization of olefins, monoolefms or diolefms), paraffinic oils, naphthenic oils (low or high viscosity), aromatic oils, mineral oils, and mixtures of these oils.
• the number-average molecular mass (Mn) of the extender oil is preferably between 200 and 25,000 g / mol, more preferably between 300 and 10,000 g / mol.
• Mn number-average molecular mass
• the number average molecular weight (Mn) of the extender oil is determined by SEC, the sample being solubilized beforehand in tetrahydrofuran at a concentration of about 1 g / l; then the solution is filtered on 0.45 ⁇ porosity filter before injection.
• the equipment is the "WATERS alliance" chromatographic chain.
• the elution solvent is tetrahydrofuran, the flow rate of 1 ml / min, the temperature of the system of 35 ° C and the analysis time of 30 min.
• the injected volume of the solution of the polymer sample is 100 ⁇ .
• the detector is a "WATERS 2410" differential refractometer and its associated software for the exploitation of chromatographic data is the “WATERS MILLENIUM” system.
• the calculated average molar masses relate to a calibration curve made with polystyrene standards.
• the person skilled in the art will know, in the light of the description and the following exemplary embodiments, to adjust the amount of plasticizer in particular according to the pneumatic object in which it is intended to be used.
• the level of plasticizing oil is preferably between 2 and 35 phr. Below the minimum indicated, the technical effect may be insufficient, while beyond the maximum stickiness of the compositions in the green state, on the mixing tools, may in some cases become prohibitive point industrial view.
• the level of plasticizing oil is even more preferably between 5 and 25 phr. II-4) Masterbatches - Rubber composition
• the masterbatches and the compositions thus produced may be used in tire applications.
• the pneumatic rubber compositions based on the masterbatches and inorganic fillers according to the invention may also comprise, in known manner, a coupling agent and / or a covering agent and a vulcanization system.
• an at least bifunctional coupling agent is used in known manner to ensure a sufficient chemical and / or physical connection between the inorganic filler ( surface of its particles) and the diene elastomer, in particular organosilanes or bifunctional polyorganosiloxanes.
• polysulfide silanes called “symmetrical” or “asymmetrical” silanes according to their particular structure, are used, as described for example in the applications WO03 / 002648 (or US 2005/016651) and WO03 / 002649 (or US 2005/016650).
• polysulphide silanes known as "symmetrical" silanes having the following general formula (III) are suitable in the following non-limiting definition:
• x is an integer of 2 to 8 (preferably 2 to 5);
• A is a divalent hydrocarbon radical (preferably C 1 -C 18 alkylene groups or C 6 -C 12 arylene groups, more particularly C 1 -C 10 alkylenes, especially C 1 -C 4 alkylenes, in particular propylene);
• R.1 radicals substituted or unsubstituted, identical or different, represent an alkyl group Ci-Cis cycloalkyl, C5-C18 aryl or C 6 -Ci8 (preferably alkyl, Ci-C 6 , cyclohexyl or phenyl, in particular alkyl, C1-C 4, more particularly methyl and / or ethyl).
• polysulphurized silanes By way of examples of polysulphurized silanes, mention may be made more particularly of the bis (C 1 -C 4 ) alkoxy (C 1 -C 4 ) alkylsilyl-C 1 -C 4 alkylsulfides (especially disulfides, trisulphides or tetrasulfides). as, for example, polysulfides of bis (3-trimethoxysilylpropyl) or bis (3-triethoxysilylpropyl).
• TESPT bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• TESPD bis (3-triethoxysilylpropyl) tetrasulfide
• polysulfides in particular disulfides, trisulphides or tetrasulfides
• bis- (monoalkoxyl (Ci-C 4 ) -dialkyl (Ci-C 4 ) silylpropyl) more particularly bis-monoethoxydimethylsilylpropyl tetrasulfide.
• POS polyorganosiloxanes
• compositions to improve their ability to implement in the green state, these agents being for example hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary amines , secondary or tertiary (for example trialkanol-amines), hydroxylated or hydrolysable POS, for example ⁇ , ⁇ - dihydroxy-polyorganosiloxanes (especially ⁇ , ⁇ -dihydroxy-polydimethylsiloxanes), fatty acids such as stearic acid.
• hydrolysable silanes such as alkylalkoxysilanes (especially alkyltriethoxysilanes), polyols, polyethers (for example polyethylene glycols), primary amines , secondary or tertiary (for example trialkanol-amines), hydroxylated or hydrolysable POS, for example ⁇ , ⁇ -
• the content of coupling agent is preferably between 0.1 and 12% by weight of the inorganic filler for a CTAB surface of 160 m 2 / g, more preferably between 4 and 10% by mass.
• inorganic filler for a CTAB surface area of 160m 2 / g; and / or the content of covering agent is preferably between 0.1 and 20% by weight of the inorganic filler for a CTAB surface of 160 m 2 / g, more preferably between 5 and 20% by mass of the inorganic filler for a surface of CTAB of 160m 2 / g.
• the coupling agent content can be adjusted to the specific surface level of the filler.
• These rubber compositions in accordance with the invention may also comprise all or part of the usual additives usually used in elastomer compositions intended for the manufacture of tires, in particular treads, such as, for example, other plasticizers, pigments protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H3M) as described for example in the application WO 02/10269, a crosslinking system based on either sulfur, or sulfur and / or peroxide donors and / or bismaleimides, vulcanization accelerators.
• other plasticizers such as, for example, other plasticizers, pigments protective agents such as anti-ozone waxes, chemical antiozonants, anti-oxidants, anti-fatigue agents, reinforcing resins, acceptors (for example phenolic novolac resin) or methylene donors (for example HMT or H
• the rubber compositions of the invention are made in suitable mixers, using two successive preparation phases according to one procedure.
• a first phase of work or thermomechanical mixing (sometimes called “non-productive” phase) at high temperature, up to a maximum temperature between 130 ° C and 200 ° C preferably between 145 ° C. and 185 ° C.
• a second mechanical working phase (sometimes referred to as a "productive" phase) at a lower temperature, typically below 120 ° C., for example between 60 ° C. and 100 ° C. ° C, finishing phase during which is incorporated the crosslinking system or vulcanization.
• all the basic constituents of the compositions of the invention are intimately incorporated, by kneading, during the so-called non-productive first phase. , that is to say that is introduced into the mixer and that is kneaded thermomechanically, in one or more steps, at least these different basic constituents until the maximum temperature between 130 ° C and 200 ° C, preferably between 145 ° C and 185 ° C.
• the plasticizing oil as well as the basic constituents of the compositions of the invention with the exception of the vulcanization system, in particular if appropriate, the inorganic filler such as silica, is incorporated in the diene elastomer and carbon black which have been previously prepared as a first masterbatch.
• this first masterbatch is made in the "liquid" phase.
• the diene elastomer in the form of latex which is in the form of elastomer particles dispersed in water, and an aqueous dispersion of carbon black have been used because, that is, say a charge dispersed in water, commonly called “slurry”.
• slurry a charge dispersed in water
• the inorganic filler and the second elastomer are incorporated in the first masterbatch also in the form of a second masterbatch which has been previously prepared.
• This second masterbatch can be prepared in particular in solid form by thermomechanical mixing of the second elastomer and the inorganic filler; it can also be prepared by any other method and in particular it can also be prepared in the liquid phase.
• this or these incorporations can be carried out simultaneously with the introduction into the mixer of the other constituents (in particular the first diene elastomer or first masterbatch) but also advantageously that this or these incorporations can be shifted in time from a few tens of seconds to a few minutes.
• an inorganic filler and a second elastomer may be introduced separately or in the form of a second master batch containing the second elastomer and the inorganic filler.
• the inorganic filler may be introduced before, after or simultaneously with the second elastomer.
• the first (non-productive) phase is carried out in a single thermomechanical step during which all the necessary constituents (in the form where appropriate) are introduced into a suitable mixer such as a conventional internal mixer. masterbatch as previously specified), any additional coating or processing agents and other miscellaneous additives, with the exception of the vulcanization system.
• the total mixing time in this non-productive phase is preferably between 1 and 15 minutes.
• the vulcanization system is then incorporated at low temperature, generally in an external mixer such as a roll mill; the whole is then mixed (productive phase) for a few minutes, for example between 2 and 15 min.
• the crosslinking system is preferably a vulcanization system, that is to say a system based on sulfur (or a sulfur-donor agent) and a primary vulcanization accelerator.
• a vulcanization system that is to say a system based on sulfur (or a sulfur-donor agent) and a primary vulcanization accelerator.
• various known secondary accelerators or vulcanization activators such as zinc oxide.
• Sulfur is used at a preferential rate of between 0.5 and 12 phr, in particular between 1 and 10 phr.
• the primary vulcanization accelerator is used at a preferred level of between 0.5 and 10 phr, more preferably between 0.5 and 5.0 phr. It is possible to use as accelerator (primary or secondary) any compound capable of acting as accelerator for vulcanization of diene elastomers in the presence of sulfur, in particular thiazole-type accelerators and their derivatives, accelerators of the thiuram type, zinc dithiocarbamates.
• accelerators are for example selected from the group consisting of 2-mercaptobenzothiazyl disulfide (abbreviated "MBTS”), tetrabenzylthiuram disulfide (“TBZTD”), N-cyclohexyl-2-benzothiazyl sulfenamide (“CBS”), N, N dicyclohexyl-2-benzothiazyl sulphenamide (“DCBS”), N-tert-butyl-2-benzothiazyl sulphenamide (“TBBS”), N-tert-butyl-2-benzothiazyl sulphenimide (“TBSI”), zinc dibenzyldithiocarbamate (“ ZBEC ”) and mixtures of these compounds.
• MBTS 2-mercaptobenzothiazyl disulfide
• TBZTD tetrabenzylthiuram disulfide
• CBS N-cyclohexyl-2-benzothiazyl sulfen
• the final composition thus obtained is then calendered, for example in the form of a sheet or a plate, in particular for a characterization in the laboratory, or else extruded in the form of a rubber profile that can be used, for example, as a tread. tires for passenger cars, trucks etc.
• the examples illustrate an improvement in the properties in terms of processability and breaking properties of rubber compositions in accordance with the invention with respect to control rubber compositions which differ from the compositions of the invention either by the CTAB specific surface of the black of the invention. carbon, either by the absence of plasticizing oil, or finally by the poor dispersion (note Z) of the carbon black in the composition.
• the following rubber compositions were prepared for some from a masterbatch made in the liquid phase of natural rubber and carbon black and for others by solid phase mixing.
• the masterbodies of diene elastomer and carbon black used in some of the following compositions are made in the liquid phase according to the process described in U.S. Patent No. 6,048,923.
• masterbatches are prepared respectively from N234 carbon black and N134 carbon black marketed by Cabot Corporation, and from natural rubber latex from fields (“fîeld latex ”) from Malaysia with a dry rubber content of 28% and a level of ammonia of 0,3%.
• control compositions TM are produced according to a conventional solid-form mixing process in which the elastomer, therefore, of the natural rubber in these examples and the reinforcing filler, respectively according to the compositions: carbon black N234 and carbon black NI 34 marketed by the Cabot Corporation.
• control rubber compositions CA are made from masterbatch A (including N234 carbon black or NI34 carbon black).
• compositions are made in the following manner:
• compositions thus obtained are then calendered either in the form of plates (thickness of 2 to 3 mm) or thin sheets of rubber for the measurement of their physical or mechanical properties, or in the form of profiles that can be used directly, after cutting and / or or assembly to the desired dimensions, for example as semi-finished products for tires, in particular as treads of tires.
• the TM1 rubber composition is prepared "en masse” from natural rubber and carbon black in solid form as detailed in paragraph III-2, the CAl and CA2 compositions not in accordance with the invention and the compositions CA3 and CA4 according to the invention are prepared from the masterbatches A according to the method detailed in paragraph III-2.
• the set of compositions regardless of the manufacturing process has the following basic formulation (in phr)
• compositions TM and CA are distinguished from each other by their note Z, the nature of the carbon black and the nature and the presence of plasticizing oil, as detailed in Table 1 which follows.
• compositions according to the invention CA3 and CA4 having a high Z score (greater than or equal to 70), as well as a black having a CTAB greater than or equal to 130 m 2 / g and a plasticizing oil according to the invention.
• composition CA4 (with a different nature of oil) surprisingly make it possible to significantly improve the processability of the composition (lower Mooney value) compared to a TM1 control composition without degrading the properties at break (stress, elongation, energy) or even improving them (composition CA4); unlike the CA1 composition (comprising a CTAB specific surface carbon black of less than 130 m 2 / g) which improves the processability but degrades the properties at break and contrary to the composition CA 2 which has degraded fracture properties and lower processability (equivalent to TM1).

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• 2012
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